package linkedlist;

/**
 * 链表
 *
 * @author: yxyi
 * @mail: yxyi@iflytek.com
 * @date: 2019-01-06
 */
public class LinkedList<E> {
    private class Node {
        public E e;
        public Node next;

        public Node(E e, Node next) {
            this.e = e;
            this.next = next;
        }

        public Node(E e) {
            this.e = e;
        }

        public Node() {
        }

        @Override
        public String toString() {
            return e.toString();
        }
    }

    // 虚拟头结点
    private Node dummyHead;
    private int size;

    public LinkedList() {
        dummyHead = new Node();
        size++;
    }

    public int getSize() {
        return size;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public void add(int index, E e) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("Add failed, Illegal index.");
        }

        Node prev = dummyHead;
        for (int i = 0; i < index; i++) {
            prev = prev.next;
        }
        prev.next = new Node(e, prev.next);

        size++;
    }

    // 头插法
    public void addFirst(E e) {
        add(0, e);
    }

    public void addLast(E e) {
        add(size, e);
    }

    public E get(int index) {
        if (index < 0 || index >= size) {
            throw new IllegalArgumentException("Get failed, Illegal index.");
        }
        Node cur = dummyHead.next;
        for (int i = 0; i < index; i++) {
            cur = cur.next;
        }
        return cur.e;
    }

    public E getFirst() {
        return get(0);
    }

    public E getLast() {
        return get(size - 1);
    }

    public void set(int index, E e) {
        if (index < 0 || index >= size) {
            throw new IllegalArgumentException("Set failed, Illegal index.");
        }
        Node cur = dummyHead.next;
        for (int i = 0; i < index; i++) {
            cur = cur.next;
        }
        cur.e = e;
    }

    public boolean contains(E e) {
        Node cur = dummyHead.next;
        while (cur != null) {
            if (cur.e.equals(e)) {
                return true;
            }
            cur = cur.next;
        }
        return false;
    }

    public E remove(int index) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("Remove failed, Illegal index.");
        }

        Node prev = dummyHead;
        for (int i = 0; i < index; i++) {
            prev = prev.next;
        }
        Node retNode = prev.next;
        prev.next = retNode.next;
        retNode.next = null;
        size--;

        return retNode.e;
    }

    public E removeFirst() {
        return remove(0);
    }

    public E removeLast() {
        return remove(size - 1);
    }

    public int find(E e) {
        Node cur = dummyHead.next;
        for (int i = 0; i < size; i++) {
            if (cur.e.equals(e)) {
                return i;
            }
        }
        return -1;
    }

    public void removeElement(E e) {
        int index = find(e);
        remove(index);
    }
}
